Non Destructive Determination Of Elastic Moduli By Two Dimensional Fourier Transformation And Laser Ultrasonic Technique

TL;DR

This paper introduces a non-destructive method combining broadband laser ultrasonics and two-dimensional Fourier transformation to measure elastic moduli of various materials with high precision.

Contribution

It presents a novel technique that uses laser ultrasonics and 2D Fourier transformation to directly determine elastic moduli non-destructively.

Findings

Successfully measured elastic moduli of paper, stainless steel, and aluminum.

Demonstrated the ability to visualize ultrasonic mode density of states.

Provided a non-destructive alternative to traditional mechanical testing.

Abstract

Broadband laser ultrasonics and two dimensional Fourier transformation are used to characterize the properties of varieties of foils and plates. Laser ultrasonics generation is achieved by use of a pulsed laser which deposits pulsed laser energy on the surface of the specimen. The displacement amplitude of the resulting broadband ultrasonic modes are monitored using a two wave mixing photo-refractive interferometer. By applying a two dimensional Fourier transformation to the detected spatial and temporal displacement waveforms, the images of density of state (DOS) for the excited ultrasounds are obtained. Results are presented for a 150 um thick paper sample, a 52.8 um stainless steel foil and a 1.27 mm thick aluminum plate. The DOS image demonstrates the ability to measure the properties of each generated ultrasonic modes and provides a direct, non destructive, measure of elastic moduli of the tested specimens